Evaluating a New Weed Killer: Blue Light and Heat

Sarah Chu (Texas A&M) preparing to test the Directed Energy Unit’s seed-killing capabilities. (Photo Credit: Philip Chu)

Harvest weed seed control is a growing area of interest and study for farmers and researchers looking to target weed seeds during harvest. My team at Texas A&M is evaluating the weed-seed-killing capabilities of a new harvest weed seed control tool that uses blue light and heat, known as the Directed Energy Unit.

The Directed Energy Unit is the brainchild of Jon Jackson, president of Global Neighbor, Inc., who tried many different light colors and wavelength combinations to kill weeds and weed seeds. He has concluded that blue light combined with a heating mid-range infrared (IR) wavelength can do something never recorded in previous scientific literature: kill weed seeds. The next question he addressed was how to implement this technology in a farmer’s field, and one option that emerged was harvest weed seed control.

Now Global Neighbor has developed a potential new method of harvest weed seed control, known as “directed energy,” which combines blue light and mid-wave infrared radiation. A machine generating the blue light and mid-IR wavelengths (i.e. directed energy) is attached to a combine and can act as a heating agent to kill weed seeds (Figure 1). There is limited research and mixed results on plant species’ response to blue light and even less information on possible response of seeds to blue light. Researchers have previously looked at heat as a way to kill weed seeds, but the temperatures needed to kill the seeds were often very high and species-dependent. For example,Palmer amaranthneeded to be exposed to 400 C (752 F) for 60 seconds to achieve complete seed kill (Norsworthy et al. 2020). 

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